Means for inspecting gun barrels



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Patented Sept. 10, 1946 Search ticos MEANS FOR INSPECTING GULN BARRELS Arthur Cyril Webb Aldis, Sparkhill, Birmingham, England, assignor to Aldis Brothers Limited, Sparkhill, Birmingham, England Application June 19, 1943, serial No. 491,525 In Great Britain April 14, 1942 8 Claims.

This invention has for its object to provide improved means for inspecting the straightness of the bores of rie and other gun barrels.

In the accompanying sheets of explanatory drawings Figure 1 is a side elevation of means constructed in accordance with the invention for inspecting the bores of rifle barrels.

Figures 2 to 6 are views illustrating to a larger scale various parts of the means shown in Figure 1, Figures 2 and 3 being respectively a front elevation and a sectional side elevation of the upper part, Figures 4 and 5 being respectively a front elevation' and a sectional side elevation of the lower part, and Figure 6 being a horizontal section on the line 6-6 of Figure 4.

Figure 7 is a plan of a modified detail.

Figures 8 and 9 are sections taken respectively on the lines 8-8 and 9-9 of Figure 7.

Figure 10 is a side elevation of a modied form of the invention.

Figures 11 and 12 are side `elevations taken at right angles to each other of another modied form of the invention.

In carrying the invention into elect as shown in Figures l to 6, I employ a vertical post a which at its lower end is secured to a supporting base b portion j ofthe bracket, the upper centre serving as an opaque mask between the light source and the bore of the rifle barrel h. In the example shown the light source o has the form of an electric lamp of high intrinsic brightness, and is adjustably mounted in a holder p in the housing n, the bulb of the lamp being preferably frosted to afford diffused illumination.

The lower centre g is open at both its upper and lower ends, and extends through the upper side of the lower bracket d which is made to a hollow form. At its outer end the upper side of the lower bracket cl is formed with a socket q in which is secured the lower end of a tubular housing r, the arrangement being such that the housing extends from the upper side of the bracket at any convenient inclination away from the post adapted to rest on a bench or on the ground, the

post and base being conveniently of hollow form. On the upper part of the post a is secured a bracket c, and on the lower part of -the post is secured another bracket d, the distance between the two brackets being dependent on the length of the rifle barrels whose bores are to be inspected. The brackets c, d, respectively carry a pair of hollow centres j, g, which are arranged coaxially with each other, and by which a rifle barrel (shown in broken lines and indicated by `h.) can be supported in a vertical position, the inner ends of the centres being shaped to a conical or like form so that they can `enter and support the adjacent ends of the rie barrel.

The upper centre f is slidably supported by and extends from the lower end of a hollow cylindrical portion i of the upper bracket c, the upper end of this centre being open and the lower end closed except for an axial ori-ce 1c of small diameter. The hollow portion y' of the bracket c is closed at its upper end by a glass window l, and contains a helical compression spring m which by acting on the upper end of the centre f tends to hold the latter in its lowermost position. On the upperbracket c is mounted a housing 'n for a light source o whereby the orifice lc in the upper centre f can be illuminated through the hollow rend of the housing r is a telescope s which at its inner end abuts against-an annular shoulder t in the socket q, the telescope having an eye-piece u at its outer end, and an object lens (not shown) in its inner end. In the interior of the lower bracket d and near its upper side is mounted a light-deflecting prism v whereby the bore of the rie barrel h, can be viewed through the telescope s, the prism being arranged and adapted to deflect the optical axis of the telescope through the lower centre g, and the clear aperture of the object lens in the telescope being larger than the diameter of the barrel bore.

To enable the rifle barrel h to be mounted in position between the hollow centres y, the upper centre f is moved upwardly against the action of the spring m. For effecting this movement a lever w is connected by a pivot a: near one end to the lupper bracket c, and is shaped at this end to a fork-like form for engaging the under sides of a pair of pins y secured to and extending from opposite sides of the upper centre f, so that downward movement of the other end of the lever causes the required upward movement of the upper centre, the latter end of the lever being provided with a chain z or being otherwise adapted to be actuated by an attendant.

At a position midway between the brackets c,

abuts against an adjustable stop 1 on the bracket d, and when the position of the barrel is reversed the upper support 4 abuts against another adjustable stop 'lfl on the bracket c.

When the rifle barrel h is mounted in position between the centres f, g, there is seen on looking into the eye-piece u of the telescope s, an image of the orifice 7c in the mask formed by the upper centre f, this image being surrounded by a bright concentric circle, with other larger concentric circles around it.

The inner concentric circle arises from rays which are reflected once from the whole surface of the bore of the rifle barrel h for a distance of two-thirds the length of the barrel measured from the viewing end, (always provided the aperture of the object lens in the telescope s includes the whole diameter of the bore).

If the bore of the rifle barrel h is straight for the whole of this two-thirds len-gth the inner circle is seen as a sharply dened thin line of uniform width, and, furthermore, if the axis of this straight portion accurately passes through the centre of the orifice 7c, this inner circle is concentric with the image of the oriiice. If the said two-thirds lengtlffthe' barrel is straight but points in a direction"- out of line with the orifice, then the inner circle will be sharply defined but eccentrically placed with regard to the image of the orifice. If, on the other hand, the said length of 'thebarrel is not straight, the circular image will appear blurred at one or more positions, or will be duplicated eccentrically.

To facilitate location of the position of the deformation in the bore to which the eccentric `circle or the blurred appearance of the circular image is attributable, I mount in the interior of vthe lower bracket d and between the prism o and the lower centre g a transversely movable slide 8 which extends through the inner and outer sides of the bracket, and which has associated with its outer end actuating means in the form of calibrated micrometer mechanism 9 mounted on the bracket. The slide 8 is provided with a straightedged aperture Il] which is situated beneath the lower centre g, and with another aperture IE)a situated between the prism v and the telescope s, the latter aperture being sufliciently large to prevent obstruction by the slide of the light path between the telescope and prism throughout the Aconveniently calibrated in terms of distances along the barrel. The'siide a may then be moved in the opposite direction to obtain a similar effect with the opposite straight edge of the aperture I0, the reading thus obtainable from the micrometer calibrations serving as a check on the previous reading.

Having examined the barrel h, from one end `the position of the barrel can be reversed so that the two-thirds length of the barrel from the opposite end may be similarly scrutinized.

In the case where a deformation is located in the barrel h, suitable means may be brought into operation for applying corrective pressure to the gun barrel, the straightening eiect of which can be observed through the telescope s by the narrow- 4 ing down of the blurred portion of the image as the pressure is applied.

In certain cases the viewing telescope s may be provided with a fine scale graticule (not shown) which is seen in the eld of View simultaneously with the image of the central orice lc and the circles surrounding it.

The brackets c, d and 2 are axially adjustable` on the post a to suit rifle barrels of diierent lengths, but are prevented from angular movement by rib-like projections I I on adjacent parts of the post.

To enable the telescope s to be adjusted in a vertical plane about the inner end of its housing T for bringing the required part of the image above described to the centre of the eld of view, the housing is of larger diameter than the body part of the telescope, and is provided at its upper end with an adjusting screw I2 and a spring-loaded plunger I3 adapted to act on opposite sides of the said body part, the outer end of the housing being shaped to prevent sideways movement of the telescope. This adjustment enables the corresponding arcs of the second and third concentric circles to be brought under observation for locating bends in the bore of the barrel. These circles arise from rays that have been respectively twice and three times reflected from the bore of the barrel. The adjustable part of the micrometer mechanism is provided with three different scales (not shown) corresponding respectively to the rst, second and third circles, and these scales can be observed through three helical windows 9a shown in Figures 1 and 5.

For aording access to the lamp o, its housing n is pivoted at I4 to the lamp holder p which is secured to the upper end of the hollow portion 7' of the bracket c, a spring-loaded ball or other detent I5 on the lamp holder being adapted by engagement with a recess in the lamp housing to hold the latter in its service position.

Instead of the slide 8 above described I may employ the modication shown in Figures 7 to 9 in which the parts similar or analogous to those above described are indicated by the same reference characters suixed by 1. In this modication a slide 81 is movable across the hollow bracket d1 by the micrometer mechanism 91 against the action of springs I6, and at right angles to this slide is arranged a second slide I'I, the latter being supported by the bracket and movable in any convenient manner. Arranged between and movable by both of the two slides 81, I'I is a third slide I8. The two slides 81, II are formed respectively with elongated openings I9, 20 arranged to prevent obstruction by these slides of the light path between the lower centre and prism above described. The third slide I8 is formed with a pair of oppositely arranged D- shaped openings 2| having their straight edges in alignment with each other and parallel with the longitudinal axis of the second slide I'I, these openings being arranged to overlap at the adjacent ends so that their aligned edges are separated by a gap as shown. By moving the second slide I'I to bring either of the D-shaped openings 2| opposite to the opening I9 in the slide 81, the straight edge of this D-shaped opening can be used in a similar manner to the corresponding edge of the previously described aperture I0 for locating a deformation in the bore of the barrel. By moving the second slide I'I to an intermediate position a comparison can be made between the eiects produced by the straight edges of both D-shaped openings 2|.

The example shown in Figure is suitable for use in inspecting the bores of gun barrels larger than rifle barrels, and the parts similar or analogous to those above described are indicated by the same reference characters suixed by 2. In this example, the lamp housing n2 is mounted on the base b2 at one side of the post a2, and the hollow centre f2 which serves as the `mask is mounted on the lamp housing and may have a rounded upper end. Also the bracket 22 carries a V-shaped crutch-like supporting member 22 for the centre of the gun barrel h2, this member being adjustable by a hand wheel 23. Moreover, the other centre g2 is mounted on a hollo-w body Z4 which is carried by the bracket c2 through the medium of a parallel motion linkage 25, the latter being loaded by a strong spring 26. On the side of the hollow body 24 remote from the linkage 25 is mounted the micrometer mechanism 92, and in'this body is mounted the transversely movable slide above described. On the upper side of the hollow body 24 is mounted a chamber 24B- containing the prism v2, and from one side of this chamber extends the housing r2 carrying the telescope s2. The hollow body 24 and the parts carried thereby form a unitary structure which can be moved upwardly to enable the gun barrel h2 to be placed in position. This movement is assisted by the spring 26 which also serves to retain the said unit in its raised position until it is again moved downwards, the arrangement being such that the effect of the spring is reduced as the hollow body 24 is moved downwards and is increased as the body is moved upwards. justable supporting screws as 2l.

Another possible form of the invention is shown in Figures 11 and 12 in which parts similar or analogous to those above described are indicated by the same reference characters suiiixed by 3. In this example the housing 13 of the telescope is provided at its inner end with an enlargement 28 from one side of which extends the micrometer mechanism 93 and which contains the transversely movable slide above described. At the side opposite to the telescope housing r3 its enlargement 28 is formed or provided with the centre g3, the latter being situated coaxially with the telescope s3. The lamp housing n3 is formed or provided with the other centre f3 which serves as the mask. Both the enlargement 28 of the telescope housing r3 and the lamp housing n3 are provided with arms 29, and are interconnected by tension springs 30 attached to the ends of the arms, the arrangement being such that the springs can lie symmetrically along the sides of the gun barrel h3.

Instead of being adapted for use by direct vision, with the eye of the observer placed near the eye-piece, the telescope in any of the examples above described may be adapted to project the image on to a screen situated at a distance from the eye-piece.

By this invention inspection of the straightness of rifle or other gun barrel bores can be carried out in a Very expeditious manner and with a minimum of fatigue. Moreover, all the operations can be carried out by artificial light. The invention is not however limited to the examples above described as subordinate details may be varied to suit requirements.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. Means for inspecting the bore of a rifle or The base b2 may be provided with ad-' other gun barrel, comprising the combination of a pair of hollow centres arranged coaxially with each other and at a suicient distance apart to enable the barrel to be mounted between them, one of the centres having a closed end which serves as a mask and has a relatively small axial orice, optical viewing means associated with the other centre and arranged so that images formed by reection of the orifice in the bore of the barrel can be inspected, a transversely movable slide arranged in association with the latter centre and the viewing means and operable to ascertain the position of a defect in the said bore by partially obstructing the light path between the associated centre and viewing means, and supporting means whereby the two centres, the optical viewing means, and the slide are supported in the required relationship.

2. Means as claimed in claim 1, in which the supporting aneans comprise in combination a supporting base, a post on the base, a bracket mounted on the post and carrying the hollow centre forming the mask, a second bracket mounted on the post and carrying the other hollow centre, the optical viewing means, and the transversely movable slide, a third bracket mounted on the post at a position (between the first and second brackets, and means on the third bracket for aiording lateral support to the barrel.

3. Means as claimed in claim 1, in which the supporting means comprise in combination a supporting base carrying the hollow centre forming the mask, a post on the base, a bracket mounted on the post and carrying the other hol-- low centre, the optical viewing means, and the transversely movable slide, a second bracket mounted on the post at a position between 'the base and the rst bracket, and means on the second bracket for affording lateral support to the barrel.

4. Means as claimed in claim 1 in which the optical viewing means comprise in combination a telescope, a hollow Ibody on which the telescope is mounted, and a prism arranged in the interior of the hollow body and adapted to deect the optical axisgouiwthe telescope through the adjacent ho1low'''entre,"`tlie latter being carried by the said hollow body. i

5. Means as claimed in claim 1, in which th supporting means comprise in combination a supporting base, a post on the base, a bracket mounted on the post and carrying the hollow centre forming the mask, a second bracket mounted on the post and carrying the other hollow centre, the optical viewing means, and the transversely movable slide, a third bracket mounted on the post at a position between the first and second brackets, a lever p-ivoted at a position between its ends to the third bracket, and end pieces on the lever for accommodating adjacent parts of the barrel.

6. Means as claimed in claim 1 and having in combination with the transversely movable slide, a second slide carried by and also movable at right angles to the rst mentioned slide, and means for moving the second slide relatively to the first slide, the two slides being formed with apertures through which the bore of the barrel can be inspected, the aperture in the second slide having a pair of parts which are displaced relatively to each other in the direction of movement of the second slide so that by appropriate movement of the second slide either of the said parts can be registered with the adjacent part of the aperture in the first slide, and the two parts of the aperture in `the second slide being formed with and situated at opposite sides .of a pair of aligned fault-locating' straight edges so arranged that by movement of the second slide relatively to the rst slide either of the said edges can be brought to a service position opposite to the aperture in the first slide for the purpose described.

7. Means for inspecting the bore of a rifle or other gun barrel, comprising the combination of amaslgipg member adapted to be mounted at one enr'we barrel and having an axial orifice which can be illuminated from .any convenient source of light,y opticaliviewing means adapted to be mounted at the other endoi the barrel and arranged so that images formed by reflection of the orice inthebore. of the barrel can be inspected, a transversely movable slide arranged in association with the viewing means and operable to ascertain the position of a defect in the said bore, by partially obstructing the light path between the interior of the barrel and the viewing means, and supporting means whereby the mask, the viewing means, and the slide are supported in the required relationship.

8. Means as claimed in claim '7, in which the supporting means comprise tension springs interconnecting the masking member and the optical viewing means and adapted to lie alongside the barrel so as to hold the said member and optical viewing means in position on the corresponding ends of the barrel, the said viewing means serving to carry the transversely movable slide. l

ARTHUR CYRIL WEBB ALDIS. 

